Development of Prototype Code for Material Balance Evaluation
in Uranium Fuel Fabrication Facility

Material Balance Evaluation (MBE) is an essential safeguards measure in bulk handling facility dealing with nuclear material. The goal of MBE is to determine whether a diversion is occurred based on quantitative statistical factors such as Material Unaccounted For (MUF) and sigma MUF. Since a uranium fuel fabrication facility is a typical bulk handling type, MBE is essentially required. In this study, the prototype code has been developed to evaluate material balance in uranium fuel fabrication facility. The main feature is that the code was designed to be used in actual facilities. So, the code has Graphical User Interface (GUI) for easy use by an end-user who may be inspection agency or facility operator. It can be controlled without professional programming knowledge to the end-user. MUF and sigma MUF are calculated based on real nuclear material accountancy data provided by facility operator. Especially, sigma MUF is calculated by IAEA’s method based on error propagation technique, and some functions for sigma MUF calculation have been additionally considered for application in actual facilities. Nuclear material accountancy approaches can be set for each key measurement point or each stratum. In addition, such information required for MBE can be set in advance and reloaded according to facility characteristics. Even it is possible to set measurement approaches according to individual items. So, the code can respond appropriately to temporary changes in facility’s nuclear material accountancy system. Detailed uncertainty analysis functions have been also introduced. A user can use it to review which measurement or which error type (random or systematic error) has higher contribution to overall sigma MUF. Since the current version is a prototype, performance improvement will be performed continuously. It is expected that the final version of this code can be utilized to evaluate material balance to check whether a diversion is occurred and to derive approach to improve nuclear material accountancy system in Pressurized Water Reactor (PWR) and Pressurized Heavy Water Reactor (PHWR) fuel fabrication facilities of South Korea.